You can use its own output against it. (Which means, ironically, it does not follow "know thyself", a maxim said to be from the Oracle at Delphi.)
Fixate on a number fairly late in the sequence (the millionths place seems to work well). If that number is 5-9, push 'f'. Otherwise, push 'd'. Keeps it pretty consistently around 0.5.
Fixate on a number fairly late in the sequence (the millionths place seems to work well). If that number is 5-9, push 'f'. Otherwise, push 'd'. Keeps it pretty consistently around 0.5.